Research published in the journal PloS One by researchers at the University of Surrey has identified the specific effect Chiari malformation has on the shape of a dog’s skull and brain.

Researchers took brain, skull and vertebrae measurements of 155 Griffon Bruxellois and compared dogs affected by the condition, with normal Griffons. They discovered that Griffons with the disease had taller foreheads and that it had also caused the shape of the brain to change, with severely affected animals having their cerebellum pushed underneath the main part of the brain.

The taller forehead makes some toy breeds look like a doll, making them more attractive to people looking to purchase a dog.

Although it can be asymptomatic, in many dogs Chiari malformation can cause headaches, problems with walking or even paralysis.

Lead author, Dr Clare Rusbridge says: “Chiari malformation can be described as trying to fit a big foot into a small shoe. It can be very painful, causing headaches and pressure on the brain and can result in fluid filled cavities in the spinal cord. Our latest discoveries will be significant in driving this research forward and hopefully allow us to identify which genes may be associated with the condition. Our next steps will be to apply our technique to other breeds with Chiari malformation and investigate more sophisticated ways of screening, so that risk of disease can be detected more easily, at an earlier age and with a single MRI scan.”

The research team wants to work with responsible breeders to use scanning technology so they can remove the condition from the breeding population.